水溶液中での銅のアノード溶解反応に及ぼす塩化物イオンと硫酸イオンの影響

抄録

The influences of chloride and sulfate ions in natural aqueous solution on the anodic dissolution of copper were investigated using electrochemical techniques. The anodic dissolution mechanisms of copper were proposed using determining the reaction parameters by the anodic polarization curves. The valencies of the copper ions were also determined using channel flow double electrode.
The anodic dissolution mechanism changed depending on the concentrations of chloride and sulfate ions in fresh water : specifically, between (1) a concentration range with trace amounts of chloride and sulfate ions, and (2) a concentration range with more than about 100ppm of chloride and sulfate ions. The anodic polarization curve didn't show pH dependence in concentration range (2), but did show pH dependence in concentration range (1). The anodic dissolution mechanisms in concentration range (2) are proposed to be as follows.
In the chloride medium :
Cu+Cl⁻=CuCl+e⁻
CuCl+Cl⁻→CuCl₂⁻
In the sulfate medium :
Cu+SO₄²⁻=CuSO₄⁻_ads+e⁻
Cu+CuSO₄⁻_ads+2SO₄²⁻
→CuSO₄⁻_ads+Cu(SO₄)₂²⁻+2e⁻
Cu(SO₄)₂²⁻=Cu²⁺+2SO₄²⁻
The influence of silica in fresh water on the anodic polarization curve was discussed.